Loading...
Please wait, while we are loading the content...
Similar Documents
Pre-harvest Factors and Fresh-cut Vegetables Quality
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chiesa, A. Frezza, D. Fraschina, Alicia Trinchero, G. C. Moccia, Stefania León, Alicia |
| Copyright Year | 2003 |
| Abstract | The characteristics and the quality of vegetable crops during storage are influenced by environmental conditions and production technology. Some preharvest factors are closely related while others act independently. To provide high quality product throughout the year, it is required to start from high quality material and to optimize the different postharvest stages. Modified atmospheres depend on the properties of the packaging material and on the respiration activity. This last one is affected by intrinsic factors, such as size, variety and maturation stage, and extrinsic factors, such as temperature, processing conditions, relative humidity and fresh-cut vegetable volume. The objective of this study was to evaluate the influence of preharvest factors on the quality of fresh cut lettuce. Three experiments were conducted with different maturity stages (harvest time and leaf expansion grade) and lettuce types. Measurements were made of weight loss, ascorbic acid and chlorogenic acid concentrations, colour changes, O2, CO2 and ethylene production in the package atmosphere, general overall visual quality and organoleptic quality. Preliminary results showed that variation in enzymatic activities was related to the lettuce type and the permeability of the packaging material to O2 and CO2. In general, a lower chlorogenic acid concentration was related to a better organoleptic quality depending on the film permeability. A higher postharvest quality on butterhead fresh cut lettuce was found with lettuce heads harvested at 45 days. Fresh cut lettuce with moderately expanded leaves showed the best general overall visual quality. Ascorbic acid concentration decreased during storage in all lettuce types. Optimization of all the steps of production, preparation and distribution of fresh cut vegetable and selection of the most suitable cultivar will yield products of extended shelf life with fresh-like quality. INTRODUCTION The characteristics and the quality of vegetable crops during storage are influenced by environmental conditions and production technology. Some pre-harvest factors are closely related while others act independently. To provide high qualitythroughout the year, it is required to start from high quality material and to optimize the different postharvest stages. The best quality of any commodity exists at the moment of harvest. From that point on, quality cannot be improved, only maintained. Many pre and postharvest factors influence the composition and quality of horticultural crops. The variety influence on nutritional value of vegetables has been reviewed by Kader (1992), who provided several examples of large genotype variation in vitamin content. Other preharvest factors include fertilisation, production technology system, nutrient and water supply, climatic conditions, temperature, light, rainfall, growing season, maturity at harvest, and harvesting method. Postharvest handling conditions also affect the nutritional quality of vegetables. During the last decade, the availability of minimally processed products has been expanded in diversity and quantity. The purpose of these products is to provide to the consumer economy of time, a product very similar to the fresh vegetable with a long shelf-life, and to guarantee foodsafety and quality. The equilibrium gas conditions of the modified atmosphere depend on the properties of the packaging material and on the Proc. Int. Conf. Quality in Chains Eds. Tijskens & Vollebregt Acta Hort. 604, ISHS 2003 154 respiration activity. This last one is affected by intrinsic factors, such as size, variety and maturation stage, and extrinsic factors, such as temperature, processing conditions, relative humidity and fresh-cut vegetable volume. The aim of this study was to evaluate the influence of preharvest factors such as harvestime, leaf expansion grade and lettuce type on the fresh cut produce. MATERIAL AND METHODS Experiment 1 In order to evaluate the postharvest behaviour of fresh cut lettuce with different maturity stages, a trial was carried out in a greenhouse, a metal structure covered with 150 μ LDT polyethylene with lateral ventilation, at the Horticulture Department (FAUBA) during fall-winter season (2001) with a butterhead lettuce cultivar Titán. Seeds were sown in multi-cellular polystyrene planter flats with 216 cells of 20 cm. A substrate with similar percentage of compost, sand and peat were used. After the nursery period, transplants were transferred to the greenhouse. Crop management was similar to a commercial one. Lettuce leaves were harvested at three maturity stages (30, 45 or 60 days). Lettuce leaves were dipped in a 200 ppm chlorine solution for 1 min at 5oC and then centrifuged at 2800 rpm for 15 sec to remove surface moisture. Minimally processed lettuce was weighted, packed in multilayered polyolefin bags PD-961EZ (oxygen permeability: 6000-8000 cm3 m2 24 h, 1 atm at 23 °C, carbon dioxide permeability: 19000-22000 cm3 m2 24 h, 1 atm at 23 °C, and water vapor transmission: 0,90-1,10 g 100 square inch, 24 h, 73oF, 100% RH). Treatments were stored at at 1°C or approximately 12 °C (12 ± 3 °C) for 7 days. Samples were taken at 0, 2, 4 and 7 days after harvest for the following measurements: a) general overall visual quality was evaluated according López Galvez et al.(1996), b) colour changes (a* value and ‘H’ hue angle) were measured with a Minolta chromameter CR-300, c) weight loss (%) was calculated, d) the O2 and CO2 concentrations in the packages were measured with a gas analyzer (Abbispack) and e) ethylene production was measured with gas cromatograph HP 5890 Serie ll. Experiment 2 The aim of this study was to evaluate the postharvest behaviour of fresh cut lettuce with different leaf expansion grade. The trial was carried out in the greenhouse described for experiment 1 during fall-winter season (2001) with a butterhead lettuce cultivar Floresta. Seeds were sown in multi-cellular polystyrene planter flats with 216 cells of 20 cm. A substrate with similar percentage of peat and vermicompost were used. After the nursery period, transplants were transferred to the greenhouse. Crop management was similar to a commercial one. Lettuce was harvested at the commercial maturity stage. Leaves were classified as: a) Outer leaves (fully expanded), length: 14-18 cm, width: 1614 cm, b) Intermediate leaves (moderately expanded), length: 10-13 cm, width: 9-13cm, and c) Inner leaves (non expanded leaves), length: ≤ 9 cm, width: ≤ 8 cm. Treatments combined leaf types such as outer leaves, intermediate leaves, inner leaves and a mix of them with two storing temperature, 1 oC or approximately 12 °C (12 ± 3 oC) for 10 days. Leaves were selected, washed, weighted (80 g per bag) and packed in multilayered polyolefin bags (PD 961-EZ) with passive modified atmosphere. Samples were taken at 0, 2, 4, 6, 8 and 10 days after harvest for the following measurements: a) general overall visual quality was evaluated according López Galvez et al. (1996), b) colour changes (a* value and ‘H’hue angle) were measured with a Minolta chromameter CR-300, c) weight loss (%) was calculated, d) the O2 and CO2 concentrations in the packages were measured with a gas analyzer (Abbispack), Serie ll, d) nitrate concentration according Cataldo et al. (1975) and dry matter content. Experiment 3 The aim of this study was to evaluate the ascorbic acid and chlorogenic acid concentration changes in different fresh cut lettuce types during the storage period. Trials |
| Starting Page | 153 |
| Ending Page | 159 |
| Page Count | 7 |
| File Format | PDF HTM / HTML |
| DOI | 10.17660/ActaHortic.2003.604.14 |
| Alternate Webpage(s) | http://www.pustakapertanianub.staff.ub.ac.id/files/2012/12/pre-harvest-factors-and-fresh-cut-vegetables-quality.pdf |
| Alternate Webpage(s) | https://doi.org/10.17660/ActaHortic.2003.604.14 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
